Blowout preventers, referred to in the oil and gas industry as BOPs, are used to prevent blowouts during the drilling and production of oil and gas wells. BOPs are installed at the wellhead for the purpose of reducing the likelihood of an undesired escape of fluid from an annular space between the casing and drill pipe or from an open hole during drilling and completion operations. On floating offshore rigs, such as semisubmersibles and drill ships, BOPs may be attached to the well on the seafloor.
BOPs are large, high-pressure valves capable of being remotely controlled. There are two basic types of BOPs, an annular-type BOP and a ram-type BOP. Typically, a plurality of BOPs are stacked on top of one another and referred to as a BOP stack. The BOP stack is attached to the wellhead.
Next to the BOPs is the well control system that monitors and controls the behavior of the subsea BOPs from the drilling rig. One of the components of the system that monitors and controls the behavior of the subsea BOPs is a subsea control pod. The subsea control pod is adapted to mount to the subsea BOP stack and provide a means of actuating and controlling the subsea BOP stack from the drilling vessel. Hydraulic lines from the drilling rig enter the subsea control pod, and the fluid is directed to the BOPs. The subsea control pod contains pilot operated control valves and pilot operated regulators which direct hydraulic fluids to the various BOP hydraulic operators controlling the BOP functions.
As such, when activating a BOP using a subsea control pod, pressurized hydraulic fluid is provided to the BOP through the valves and passages of the subsea control pod. Due to the high pressures of the hydraulic fluid, a pressure surge or wave caused from suddenly starting or stopping fluid flow, commonly referred to as fluid hammer or hydraulic shock, may reduce the life expectancy of the valves, hoses, and/or other components of the subsea control pod. Accordingly, it remains a priority to reduce the effects of a fluid hammer, for example, to increase the life expectancy of the components of a subsea control pod, particularly in these remote locations where maintenance may be difficult.